We are moving from MPC to CMake.
We provide a lib with some samples. The samples are coming with makefiles.
The problem is that the makefiles, generated by cmake contains absolute paths but not relative ones:
# The main all target
all: cmake_check_build_system
cd /.../Projects/cpp_trunk && $(CMAKE_COMMAND) -E cmake_progress_start /.../Projects/cpp_trunk/CMakeFiles /.../Projects/cpp_trunk/samples/CMakeFiles/progress.make
cd /.../Projects/cpp_trunk && $(MAKE) -f CMakeFiles/Makefile2 samples/all
$(CMAKE_COMMAND) -E cmake_progress_start /.../cpp_trunk/CMakeFiles 0
So, when it is copied it's become broken.
It there any way to work it around?
UPD: I have read the FAQ, but my question is still taking place, perhaps somebody managed to get around?
What I've done to get around this sort of thing is write a small wrapper Makefile around cmake. I put the Makefile at the project root, with contents like this:
all: cmake
cmake:
[ -f build/CMakeCache.txt ] && [ "$$(pwd)" != "$$(grep 'CMAKE_HOME_DIRECTORY:INTERNAL' build/CMakeCache.txt | cut -d '=' -f 2)" ] \
&& rm -rf build || true
mkdir -p build && cd build && cmake ..
make -C build
clean:
rm -rf build
There's probably a cleaner way to do it, but it works for me:
make # build in one directory
cd ..
olddir=$(basename $OLDPWD) && rsync -ravz $olddir ${olddir}-test && cd ${olddir}-test # copy to another directory
make # running make in the new dir triggers a full rebuild
make # running make a second time in the new dir does not rebuild
The makefiles created by CMake are not part of your source code base. The CMakeLists.txt files that you use as input to CMake are part of your source code base. When you copy your source code to a different place and want to build it there, build from your source code. That means re-running CMake. (And that's your workaround.)
I've been using CMake for over ten years continuously on one project. One of the handy tricks my team has learned is that you can have multiple copies of one part of your source code base on one development host that all share the same copy of the rest of your source code base. Try doing that with relative paths! We rely on the fact that every time we build source code in a new build directory, CMake will figure out the correct paths to all the source files, which are not necessarily the same relative to the new build directory as they were in the previous build.
The build files that are generated by cmake (makefiles, ninja files, etc), are going to have hardcoded paths and other not-portable stuff in them. That's ok. Treat them as temporary files that are part of the build process. You will only version the CMakeLists.txt files, and then generate new makefiles (or whatever) on other machines or in other directories when you check it out. You can even have different people on the team using different build files - one person using makefiles, one person using eclipse+ninja, etc, all generated by cmake.
Related
I have to merge cmake's makes and makes in our build systems. The build systems are supposed to be able to work with both options make and cmake. The problem is that cmake's make exports do not contain all variables and settings, which need to be set as make in our build systems. Basically, we use three complicated build systems for cross platform development and I do not like setting everything on many places, because then it is hard to maintain the system like that.
E g. makefiles from many coders in all build system contains include common file like:
include $(PROJECT_CONF_DIR)/common/something.mk
How to solute it by cmake? I do not like modifying coders' CMakeLists.txt (max. one row solution for them) and I also do not like modifying cmake exports into make files.
Basically, I need to put somewhere in cmake command or cmake's export (the best) some link which will lead to include all 'garbage' expecting by our build tool chains.
Make sure that CMakeLists.txt can contain many cmake subprojects and libraries.
e.g. Our build system from makefiles contains something like:
directories-default:
mkdir -p $(BUILD_DIR)
mkdir -p $(OBJ_DIR)
I need to implement it somehow in cmake include.
To be able to run make directories-default after configuration, you have to create a target. You can make a target that will call a custom command, which would run the shell commands you need.
add_custom_target(directories-default COMMAND mkdir -p "dir1" COMMAND mkdir -p "dir2")
The syntax above will result in a target that is always considered out of date, ie every time you run make directories-default (or make all), the commands will be executed. If you don't want to re-run the command every time you can use a custom command:
add_custom_command(OUTPUT "dir3" "dir4" COMMAND mkdir -p "dir3" COMMAND mkdir -p "dir4")
add_custom_target(directories-default2 DEPENDS "dir3" "dir4")
Here make directories-default2 will only run the commands the first time you run it. You can also create a dependency chain of commands using the DEPENDS argument in add_custom_command.
I don't have much knowledge about cmake. I installed a package libfreenect2 following the instructions on their github page. The instructions were as follows-
Clone the repository. And follow the cmake step:
cd ..
mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME/freenect2
make
make install
However, after installing I realised the program/package that required libfreenect2 as a dependency required me to use:
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME/freenect2 -DENABLE_CXX11=ON
You may have noticed, it required me to use an extra flag -DENABLE_CXX11=ON. How can I fix this? How can I set ENABLE_CXX11=ON after the whole make process has been completed? By the way what does -D do? (are these -DXXX things called options or flag)
In case your answer is to repeat the whole process again then kindly guide me through the step by step process of deleting the correct files. I don't want to delete other dependencies.
Here are some other stackoverflow answers relating to cmake-
set cmake option(), cmake option to include a directory, What does cmake do
SOLUTION - I used the accepted solution to enable the flag. Even though it worked for my problem (libfreenect2) still it will be amazing if someone could provide an answer which doesn't involve reinstalling.
My warm suggestion would be to repeat the process with that option ON.
First you should delete what was previously generated.
The sequence of commands to follow is the following:
rm -rf build
rm -rf $HOME/freenect2
just to be entirely sure you start from a "clean state".
I don't see the need to do rm -rf $HOME/freenect2 as that files/dir will be overwritten by the new install, but shouldn't hurt.
You can also try the suggestion in the SO post mentioned in one of the comments.
Then repeat the process from the root dir of libfreenect2:
mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME/freenect2 -DENABLE_CXX11=ON
make
make install
Alternatively, if you're entirely sure that you will build libfreenect2 always with that option ENABLE_CXX11=ON, you could explicitely set it ON once and for all in the CMakeLists.txt of libfreenect2, specifically changing the line:
OPTION(ENABLE_CXX11 "Enable C++11 support" OFF)
into
OPTION(ENABLE_CXX11 "Enable C++11 support" ON)
In this last case, you will just need to do
mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME/freenect2
make
make install
of course after you've cleaned as explained at the beginning.
About -D for CMake, it allows you to pass options. Directly from the documentation:
-D <var>:<type>=<value>
Create a cmake cache entry.
When cmake is first run in an empty build tree, it creates a
CMakeCache.txt file and populates it with customizable settings for
the project. This option may be used to specify a setting that takes
priority over the project’s default value. The option may be repeated
for as many cache entries as desired.
So if there's some project default options that one wants to change/overwrite than it can be done with this.
I have the following source directory structure
src:
dir1: c++ files, Makefile
dir2: perl/python scripts, Makefile
build:
bin:
binary-executables
bin-subdir: I want my perl/python files to be copied during the build process.
Also, When I do a make install, will the bin-subdir be copied into install/bin by default or I have to specify that as well?
Basically, when you run make X, you are telling Make to find target X in your Makefile. So if you have no install: target, nothing will happen. All of this really depends what is in your Makefiles. If you want to copy your perl/python files into the build directory, one way to do so is to write a Makefile target that runs a *sh command like mv dir2/*.pyc build; mv dir2/*.pl build, and require that target somewhere else in your Makefile. If you need a good Makefile tutorial, here's one that I started with.
I just want to know what do I need to write in the Makefile.am to create a directory called build in the same directory where Makefile.am is.
Think about your question carefully: Do you really want to create build in the same directory as Makefile.am, or in the current working directory when configure is called? These are not always the same thing: the GNU build system is meant to support out-of-tree builds (with a potentially read-only $srcdir), so the end user should expect the following to work:
$ tar xf autofoo-1.2.tar.gz
$ mkdir autofoo-build
$ cd autofoo-build
$ ../autofoo-1.2/configure
$ make
$ sudo make install
Now, the easiest way I have found to create a directory is not to use Makefile.am at all, but instead to make config.status do it (which is the shell script that does all of the template substitutions at the end of configure, turning Makefile.in into Makefile, config.h.in into config.h and so on). In configure.ac, put the following:
AC_CONFIG_COMMANDS([mkdir], [$MKDIR_P build])
You would need to write:
build:
test -d ${srcdir}/build || mkdir ${srcdir}/build
but you really do not want to do that. The source directory should be considered read-only. If you simply want to create a directory named build in the build directory, just do
build:
test -d build || mkdir build
How do I tell cmake where it should output its build data?
Let's say I have a dir with the source code called src/,
and then since cmake outputs a lot of files I would like him to put all of that in
a dir called build/.
BUT I would like him to put the generated Makefile in the project root,
so I don't have to go into the build dir to build the application.
Is this possible with cmake?
I have managed to get the cmake out put if I fun cmake in the build dir like this:
cd build/
cmake ../src/
make
./hello
But it would be nice to stay in the project root and type something like this
cmake
make
./hello
I guess that I need to put a CMakeList.txt in the project root with some magic commands telling him where he could put the object files and where he can find the source code.
Thanks
Update:
Since my question is a little bit vague.
After I have run the cmake commands this is how I would like my tree to look like:
src/CMakeLists.txt
src/hello.c
src/hello.h
build/CMakeCache.txt
build/CMakeFiles/
build/cmake_install.cmake
CMakeLists.txt
Makefile
So the question is how should the CMakeLists.txt look like in this setup.
CMakeLists.txt
src/CMakeLists.txt
But maybe that is not possible?
BUT I would like him to put the generated Makefile in the project root, so I don't have to go into the build
dir to build the application.
cmake not designed for that, as I know,
BUT you can stay in the project root and type:
make -C build
./hello
with custom build rules or set_target_properties,
you can force cmake to put result executable to
sources directory or you can use
./build/hello
Type "cd build && cmake .." you need only once,
after that make will automaticaly start cmake, if something
changed.
cmake wants you to have a fresh build directory.
Okay, i get what you want. I think, you can achieve this with some machinery in CMakeLists.txt. Of course, it's not option if you are not project developer.
In root CMakeLists.txt you can add file(WRITE ...) command, which would write Makefile into ${CMAKE_SOURCE_DIR}. This Makefile would contain these commands for every target:
<target>:
cd ${CMAKE_BUILD_DIR} && ${CMAKE_MAKE_PROGRAM} <target>
So, now you can run make from source dir and it will build your project in build dir.
Simply use
cmake .
make
in your src directory. The (.) dot on unix systems addresses the current directory. Keep in mind doing so is actually not recommended since there will be a lot of build files in your src directory you'll have to clean up afterwards or at release time.